Activity

Rocket powered by baking soda and vinegar (demonstration)

Summary
An adult sets off a rocket outdoors, powered by the chemical reaction of baking soda and vinegar. Students figure out how the rocket works.
Science content
Chemistry: States of Matter, Properties of Materials (K-7)
Chemistry: Atoms, Molecules (3-7)
Chemistry: Chemical Changes (2, 7)
Physics: Motion and Forces, Newton’s Laws, Gravity (K, 2, 6)
Earth/Space: Extreme Environments, Space Exploration (6)
Materials
  • baking soda
  • tissue to wrap baking soda in
  • vinegar (can also do with lemon juice)
  • rocket
  • cloth for clean up
  • water to rinse out rocket
  • open site to set off rocket
  • sturdy flat base to stand rocket on if grass is bumpy
  • optional: molecule models - 3 red oxygen atoms, two white hydrogen atoms, one black carbon atom and 6 bonds for each student/student pair
Procedure

It is a rocket powered by a chemical reaction.
Baking soda and vinegar react to make gas, which is trapped in the corked bottle. When the gas pressure is great enough to push the cork out, the rocket flies up in the air.

Pour 200ml vinegar into the bottle.
Add a couple of teaspoons of baking soda to the tissue, and twist the ends to package it, but so that it is narrow enough to fit through the mouth of the bottle.
Make sure that you are away from the students, then push the baking soda package into the bottle. Cork the bottle, then stand it up for take off.
Stand back. Even if it takes a little time, the tissue will eventually disintegrate and release the baking soda into the vinegar, and set off the rocket.
If you think gas is escaping more slowly (around the side of the cork, for example) and the rocket will not fly, kick it over with your foot before reaching down to take it apart (so the rocket does not go off in your face), and reset it.

A rocket nicely demonstrates Newton's 3rd Law - for every action there is an equal and opposite reaction. The gas and liquid shooting downwards out of the bottle (the 'action') pushes on the bottle ('reaction') sending it upwards.

For a dramatic demonstration of Newton's 2nd Law, set the bottle right-side-up for take off (with the cork pointing upwards), making sure there is a mound of gravel or something around the base of the bottle so that it will not tip over. With the same amount of baking soda and vinegar, the cork flies way higher than the bottle (be careful with set up - the cork shoots out of the bottle really fast). With the same force, the smaller mass of the cork accelerates more than the larger mass of the bottle.

With older students, model the chemical reaction that powers the rocket:
Give each student a model of HCO3 (baking soda) and H (the atom that makes vinegar acidic). We started with these in the rocket.
The baking soda and vinegar molecules react and rearrange to make two new molecules. Ask students to figure out what these molecules are, giving them the hint that one of them is water.
The products of the reaction are water (H2O) and carbon dioxide (CO2).
Carbon dioxide is a gas, and as more and more of it is made by the chemical reaction, the gas builds up in pressure until it blows the cork out of the bottle.
Once the cork is released, the gas can escape by shooting out of the bottom of the rocket. This force propels the rocket upwards.

A rocket that goes to space acts on the same principal of action and reaction: the exhaust is expelled out of the back of the rocket, and this force is countered by a force on the rocket that propels it upwards.

Purchase molecule models online at Indigo Instruments https://www.indigoinstruments.com

Grades taught
Gr K
Gr 1
Gr 2
Gr 3
Gr 4
Gr 5
Gr 6
Gr 7